Apparatus and process for the controlled reduction of organic material via microwave radiation

Abstract

A controllable, continuous-feed system and process for the reduction or depolymerization of organic materials using microwave energy in a reducing, substantially oxygen-reduced atmosphere. The microwave energy is generated by a plurality of magnetrons in a microwave tunnel. Gaseous products may be extracted from the microwave tunnel for recycling and/or analysis. A collector such as a liquid trap may be used to separately collect floating and sinking constituents of the solid products while preventing the escape of the reducing atmosphere from the system.

What is claimed is: 
     
       1. A system for reduction of organic materials, comprising:
 an infeed module for receiving material comprising organic materials and conveying the material into a reducing atmosphere, the infeed module comprising:
 an infeed conveyor, for conveying the material through the infeed module, 
 a first purge chamber, 
 a first closure for isolating the first purge chamber from an ambient atmosphere outside the system, 
 a gas injection system in communication with the first purge chamber, for injecting a reducing gas to displace air from the first purge chamber to create a reducing atmosphere having a lowered concentration of oxygen in the first purge chamber, and 
 a second purge chamber in sealed communication with the first purge chamber and selectively isolated therefrom by a closure, whereby air in the second purge chamber is displaced by the reducing gas or another reducing gas to create a second reducing atmosphere in the second purge chamber having a lower concentration of oxygen than the reducing atmosphere in the first purge chamber; 
 a microwave tunnel, the microwave tunnel being in sealed communication with the infeed module for isolating the microwave tunnel from the ambient atmosphere outside the system, the microwave tunnel comprising:
 a microwave-impervious microwave chamber comprising a plurality of magnetrons for generating microwave radiation and at least one port for removal of process gas products, and 
 a tunnel conveyor for receiving the material from the infeed module and transporting the material through the microwave chamber, and 
 at least a second closure for selectively isolating the second purge chamber from the microwave tunnel; and 
 at least one controller for controlling process parameters of the infeed module and the microwave tunnel, wherein the controller is configured to execute a purging process by controlling the closures of the first and second purge chambers and the gas injection system to purge the first and second purge chambers to respective predetermined oxygen levels and the predetermined oxygen level of the second purge chamber is less than the predetermined oxygen level of the first purge chamber. 
 
 
 
     
     
       2. The system of  claim 1  wherein the infeed module further comprises a weight conveyor for detecting a weight of the materials. 
     
     
       3. The system of  claim 1  wherein the first and second closures comprise flop gates. 
     
     
       4. The system of  claim 1  wherein the reducing gas is nitrogen. 
     
     
       5. The system of  claim 1  wherein the first purge chamber comprises at least one vent valve, which when opened allows gas to escape from the first purge chamber. 
     
     
       6. The system of  claim 1  further comprising an oxygen sensor for the first purge chamber for monitoring a concentration of oxygen in the first purge chamber. 
     
     
       7. The system of  claim 1  further comprising a pressure switch for the first purge chamber to limit a pressure in the first purge chamber. 
     
     
       8. The system of  claim 1  wherein each magnetron is provided with a waveguide to focus the microwave radiation generated by the magnetron. 
     
     
       9. The system of  claim 1  wherein the microwave tunnel further comprises a port valve for each of the at least one ports. 
     
     
       10. The system of  claim 9  further comprising a compressor for drawing processes gas products out of the microwave chamber through the at least one port. 
     
     
       11. The system of  claim 10  further comprising a condenser for condensing at least one component of the process gas product into a liquid. 
     
     
       12. The system of  claim 1  further comprising an outfeed module, the outfeed module being adapted for sealed communication with the microwave tunnel, for preventing the escape of the process gas and separating at least one solid product for collection, the outfeed module comprising:
 a liquid sealed portion having an opening in sealed communication with the exit of the microwave tunnel, a floor, walls and ceiling, the floor, walls and ceiling being liquid sealed, whereby a liquid may be held in the liquid sealed portion intersecting with a low portion of the ceiling; and 
 at least one mechanism for the collection of the at least one solid product. 
 
     
     
       13. The outfeed module of  claim 12  wherein the ceiling is partially submerged and the at least one solid product comprises a product that floats on the liquid, wherein at least one mechanism for the collection of the solid product comprises a paddle wheel assembly for collecting the floating product from the surface of the liquid, the paddle wheel assembly having paddle blades and wherein the paddle wheel assembly is mounted such that a portion of the paddle blades is exposed above the surface of the liquid to push the floating product toward a floating product conveyor for removing the floating product from the liquid. 
     
     
       14. The system of  claim 12  wherein a downstream end of the tunnel conveyor is positioned such that the solid products thereon are directed into the liquid of the outfeed module. 
     
     
       15. The system of  claim 13  wherein the floating product conveyor is a screw conveyor. 
     
     
       16. The outfeed module of  claim 12  wherein the at least one solid product comprises a product that sinks in the liquid and wherein at least one mechanism for the collection of the at least one solid product comprises a collection conveyor in the liquid sealed portion onto which the sinking product sinks for removal of the sinking product from the liquid. 
     
     
       17. The system of  claim 1  wherein the microwave tunnel further comprises microwave impermeable curtains at the entrance and exit of the microwave tunnel.